Any necessary truth, whether a priori or a posteriori, could not have turned out otherwise

Proper names are rigid designators.

I wish I could have skipped college.

Certainly the philosopher of 'possible worlds' must take care that his technical apparatus not push him to ask questions whose meaningfulness is not supported by our original intuitions of possibility that gave the apparatus its point.

I just hate sitting and writing - I had to do that in school. Plus, I have terrible handwriting.

Any necessary truth, whether a priori or a posteriori, could not have turned out otherwise

Let's call something a rigid designator if in every possible world it designates the same object, a non-rigid or accidental designator if that is not the case. Of course we don't require that the objects exist in all possible worlds.... When we think of a property as essential to an object we usually mean that it is true of that object in any case where it would have existed. A rigid designator of a necessary existent can be called strongly rigid.